In assaying bismuth ore, place pieces of ore in the scorifier, and put
it under the muffle in a hot furnace; as soon as they are heated, they
drip with bismuth, which runs together into a button.
it under the muffle in a hot furnace; as soon as they are heated, they
drip with bismuth, which runs together into a button.
Quicksilver ore is usually tested by mixing one part of broken ore
with three-parts of charcoal dust and a handful of salt. Put the mixture into
a crucible or a pot or a jar, cover it with a lid, seal it with lute, place it on
glowing charcoal, and as soon as a burnt cinnabar colour shows in it, take
out the vessel; for if you continue the heat too long the mixture exhales the
quicksilver with the fumes. The quicksilver itself, when it has become cool, is
found in the bottom of the crucible or other vessel. Another way is to place
broken ore in a gourd-shaped earthen vessel, put it in the assay furnace,
and cover with an operculum which has a long spout; under the spout, put
an ampulla to receive the quicksilver which distills. Cold water should be
poured into the ampulla, so that the quicksilver which has been heated by the
fire may be continuously cooled and gathered together, for the quicksilver
is borne over by the force of the fire, and flows down through the spout of
the operculum into the ampulla. We also assay quicksilver ore in the very
same way in which we smelt it. This I will explain in its proper place.
with three-parts of charcoal dust and a handful of salt. Put the mixture into
a crucible or a pot or a jar, cover it with a lid, seal it with lute, place it on
glowing charcoal, and as soon as a burnt cinnabar colour shows in it, take
out the vessel; for if you continue the heat too long the mixture exhales the
quicksilver with the fumes. The quicksilver itself, when it has become cool, is
found in the bottom of the crucible or other vessel. Another way is to place
broken ore in a gourd-shaped earthen vessel, put it in the assay furnace,
and cover with an operculum which has a long spout; under the spout, put
an ampulla to receive the quicksilver which distills. Cold water should be
poured into the ampulla, so that the quicksilver which has been heated by the
fire may be continuously cooled and gathered together, for the quicksilver
is borne over by the force of the fire, and flows down through the spout of
the operculum into the ampulla. We also assay quicksilver ore in the very
same way in which we smelt it. This I will explain in its proper place.
Lastly, we assay iron ore in the forge of a blacksmith.
Such ore is burned,
crushed, washed, and dried; a magnet is laid over the concentrates, and
the particles of iron are attracted to it; these are wiped off with a brush,
and are caught in a crucible, the magnet being continually passed over the
concentrates and the particles wiped off, so long as there remain any particles
which the magnet can attract to it. These particles are heated in the crucible
with saltpetre until they melt, and an iron button is melted out of them.
If the magnet easily and quickly attracts the particles to it, we infer that the
ore is rich in iron; if slowly, that it is poor; if it appears actually to repel
the ore, then it contains little or no iron. This is enough for the assaying of
ores.
crushed, washed, and dried; a magnet is laid over the concentrates, and
the particles of iron are attracted to it; these are wiped off with a brush,
and are caught in a crucible, the magnet being continually passed over the
concentrates and the particles wiped off, so long as there remain any particles
which the magnet can attract to it. These particles are heated in the crucible
with saltpetre until they melt, and an iron button is melted out of them.
If the magnet easily and quickly attracts the particles to it, we infer that the
ore is rich in iron; if slowly, that it is poor; if it appears actually to repel
the ore, then it contains little or no iron. This is enough for the assaying of
ores.
I will now speak of the assaying of the metal alloys.
This is done both
by coiners and merchants who buy and sell metal, and by miners, but most
of all by the owners and mine masters, and by the owners and masters of
the works in which the metals are smelted, or in which one metal is parted
from another.
by coiners and merchants who buy and sell metal, and by miners, but most
of all by the owners and mine masters, and by the owners and masters of
the works in which the metals are smelted, or in which one metal is parted
from another.
First I will describe the way assays are usually made to ascertain what
portion of precious metal is contained in base metal. Gold and silver are
now reckoned as precious metals and all the others as base metals. Once
upon a time the base metals were burned up, in order that the precious metals
should be left pure; the Ancients even discovered by such burning what
portion of gold was contained in silver, and in this way all the silver was
consumed, which was no small loss. However, the famous mathematician,
Archimedes31, to gratify King Hiero, invented a method of testing the silver,
portion of precious metal is contained in base metal. Gold and silver are
now reckoned as precious metals and all the others as base metals. Once
upon a time the base metals were burned up, in order that the precious metals
should be left pure; the Ancients even discovered by such burning what
portion of gold was contained in silver, and in this way all the silver was
consumed, which was no small loss. However, the famous mathematician,
Archimedes31, to gratify King Hiero, invented a method of testing the silver,
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